# This file contains modules common to various models

import math

import numpy as np
import requests
import torch
import torch.nn as nn
from PIL import Image, ImageDraw

from src.external.yolo5_face.utils_yolo.datasets import letterbox
from src.external.yolo5_face.utils_yolo.general import non_max_suppression, make_divisible, scale_coords, xyxy2xywh
from src.external.yolo5_face.utils_yolo.plots import color_list

def autopad(k, p=None):  # kernel, padding
    # Pad to 'same'
    if p is None:
        p = k // 2 if isinstance(k, int) else [x // 2 for x in k]  # auto-pad
    return p

def channel_shuffle(x, groups):
    batchsize, num_channels, height, width = x.data.size()
    channels_per_group = num_channels // groups

    # reshape
    x = x.view(batchsize, groups, channels_per_group, height, width)
    x = torch.transpose(x, 1, 2).contiguous()

    # flatten
    x = x.view(batchsize, -1, height, width)
    return x

def DWConv(c1, c2, k=1, s=1, act=True):
    # Depthwise convolution
    return Conv(c1, c2, k, s, g=math.gcd(c1, c2), act=act)

class Conv(nn.Module):
    # Standard convolution
    def __init__(self, c1, c2, k=1, s=1, p=None, g=1, act=True):  # ch_in, ch_out, kernel, stride, padding, groups
        super(Conv, self).__init__()
        self.conv = nn.Conv2d(c1, c2, k, s, autopad(k, p), groups=g, bias=False)
        self.bn = nn.BatchNorm2d(c2)
        self.act = nn.SiLU() if act is True else (act if isinstance(act, nn.Module) else nn.Identity())
        #self.act = self.act = nn.LeakyReLU(0.1, inplace=True) if act is True else (act if isinstance(act, nn.Module) else nn.Identity())

    def forward(self, x):
        return self.act(self.bn(self.conv(x)))

    def fuseforward(self, x):
        return self.act(self.conv(x))

class StemBlock(nn.Module):
    def __init__(self, c1, c2, k=3, s=2, p=None, g=1, act=True):
        super(StemBlock, self).__init__()
        self.stem_1 = Conv(c1, c2, k, s, p, g, act)
        self.stem_2a = Conv(c2, c2 // 2, 1, 1, 0)
        self.stem_2b = Conv(c2 // 2, c2, 3, 2, 1)
        self.stem_2p = nn.MaxPool2d(kernel_size=2,stride=2,ceil_mode=True)
        self.stem_3 = Conv(c2 * 2, c2, 1, 1, 0)

    def forward(self, x):
        stem_1_out  = self.stem_1(x)
        stem_2a_out = self.stem_2a(stem_1_out)
        stem_2b_out = self.stem_2b(stem_2a_out)
        stem_2p_out = self.stem_2p(stem_1_out)
        out = self.stem_3(torch.cat((stem_2b_out,stem_2p_out),1))
        return out

class Bottleneck(nn.Module):
    # Standard bottleneck
    def __init__(self, c1, c2, shortcut=True, g=1, e=0.5):  # ch_in, ch_out, shortcut, groups, expansion
        super(Bottleneck, self).__init__()
        c_ = int(c2 * e)  # hidden channels
        self.cv1 = Conv(c1, c_, 1, 1)
        self.cv2 = Conv(c_, c2, 3, 1, g=g)
        self.add = shortcut and c1 == c2

    def forward(self, x):
        return x + self.cv2(self.cv1(x)) if self.add else self.cv2(self.cv1(x))

class BottleneckCSP(nn.Module):
    # CSP Bottleneck https://github.com/WongKinYiu/CrossStagePartialNetworks
    def __init__(self, c1, c2, n=1, shortcut=True, g=1, e=0.5):  # ch_in, ch_out, number, shortcut, groups, expansion
        super(BottleneckCSP, self).__init__()
        c_ = int(c2 * e)  # hidden channels
        self.cv1 = Conv(c1, c_, 1, 1)
        self.cv2 = nn.Conv2d(c1, c_, 1, 1, bias=False)
        self.cv3 = nn.Conv2d(c_, c_, 1, 1, bias=False)
        self.cv4 = Conv(2 * c_, c2, 1, 1)
        self.bn = nn.BatchNorm2d(2 * c_)  # applied to cat(cv2, cv3)
        self.act = nn.LeakyReLU(0.1, inplace=True)
        self.m = nn.Sequential(*[Bottleneck(c_, c_, shortcut, g, e=1.0) for _ in range(n)])

    def forward(self, x):
        y1 = self.cv3(self.m(self.cv1(x)))
        y2 = self.cv2(x)
        return self.cv4(self.act(self.bn(torch.cat((y1, y2), dim=1))))


class C3(nn.Module):
    # CSP Bottleneck with 3 convolutions
    def __init__(self, c1, c2, n=1, shortcut=True, g=1, e=0.5):  # ch_in, ch_out, number, shortcut, groups, expansion
        super(C3, self).__init__()
        c_ = int(c2 * e)  # hidden channels
        self.cv1 = Conv(c1, c_, 1, 1)
        self.cv2 = Conv(c1, c_, 1, 1)
        self.cv3 = Conv(2 * c_, c2, 1)  # act=FReLU(c2)
        self.m = nn.Sequential(*[Bottleneck(c_, c_, shortcut, g, e=1.0) for _ in range(n)])

    def forward(self, x):
        return self.cv3(torch.cat((self.m(self.cv1(x)), self.cv2(x)), dim=1))

class ShuffleV2Block(nn.Module):
    def __init__(self, inp, oup, stride):
        super(ShuffleV2Block, self).__init__()

        if not (1 <= stride <= 3):
            raise ValueError('illegal stride value')
        self.stride = stride

        branch_features = oup // 2
        assert (self.stride != 1) or (inp == branch_features << 1)

        if self.stride > 1:
            self.branch1 = nn.Sequential(
                self.depthwise_conv(inp, inp, kernel_size=3, stride=self.stride, padding=1),
                nn.BatchNorm2d(inp),
                nn.Conv2d(inp, branch_features, kernel_size=1, stride=1, padding=0, bias=False),
                nn.BatchNorm2d(branch_features),
                nn.SiLU(),
            )
        else:
            self.branch1 = nn.Sequential()

        self.branch2 = nn.Sequential(
            nn.Conv2d(inp if (self.stride > 1) else branch_features, branch_features, kernel_size=1, stride=1, padding=0, bias=False),
            nn.BatchNorm2d(branch_features),
            nn.SiLU(),
            self.depthwise_conv(branch_features, branch_features, kernel_size=3, stride=self.stride, padding=1),
            nn.BatchNorm2d(branch_features),
            nn.Conv2d(branch_features, branch_features, kernel_size=1, stride=1, padding=0, bias=False),
            nn.BatchNorm2d(branch_features),
            nn.SiLU(),
        )

    @staticmethod
    def depthwise_conv(i, o, kernel_size, stride=1, padding=0, bias=False):
        return nn.Conv2d(i, o, kernel_size, stride, padding, bias=bias, groups=i)

    def forward(self, x):
        if self.stride == 1:
            x1, x2 = x.chunk(2, dim=1)
            out = torch.cat((x1, self.branch2(x2)), dim=1)
        else:
            out = torch.cat((self.branch1(x), self.branch2(x)), dim=1)
        out = channel_shuffle(out, 2)
        return out
    
class BlazeBlock(nn.Module):
    def __init__(self, in_channels,out_channels,mid_channels=None,stride=1):
        super(BlazeBlock, self).__init__()
        mid_channels = mid_channels or in_channels
        assert stride in [1, 2]
        if stride>1:
            self.use_pool = True
        else:
            self.use_pool = False

        self.branch1 = nn.Sequential(
            nn.Conv2d(in_channels=in_channels,out_channels=mid_channels,kernel_size=5,stride=stride,padding=2,groups=in_channels),
            nn.BatchNorm2d(mid_channels),
            nn.Conv2d(in_channels=mid_channels,out_channels=out_channels,kernel_size=1,stride=1),
            nn.BatchNorm2d(out_channels),
        )

        if self.use_pool:
            self.shortcut = nn.Sequential(
                nn.MaxPool2d(kernel_size=stride, stride=stride),
                nn.Conv2d(in_channels=in_channels, out_channels=out_channels, kernel_size=1, stride=1),
                nn.BatchNorm2d(out_channels),
            )

        self.relu = nn.SiLU(inplace=True)

    def forward(self, x):
        branch1 = self.branch1(x)
        out = (branch1+self.shortcut(x)) if self.use_pool else (branch1+x)
        return self.relu(out)    
  
class DoubleBlazeBlock(nn.Module):
    def __init__(self,in_channels,out_channels,mid_channels=None,stride=1):
        super(DoubleBlazeBlock, self).__init__()
        mid_channels = mid_channels or in_channels
        assert stride in [1, 2]
        if stride > 1:
            self.use_pool = True
        else:
            self.use_pool = False

        self.branch1 = nn.Sequential(
            nn.Conv2d(in_channels=in_channels, out_channels=in_channels, kernel_size=5, stride=stride,padding=2,groups=in_channels),
            nn.BatchNorm2d(in_channels),
            nn.Conv2d(in_channels=in_channels, out_channels=mid_channels, kernel_size=1, stride=1),
            nn.BatchNorm2d(mid_channels),
            nn.SiLU(inplace=True),
            nn.Conv2d(in_channels=mid_channels, out_channels=mid_channels, kernel_size=5, stride=1,padding=2),
            nn.BatchNorm2d(mid_channels),
            nn.Conv2d(in_channels=mid_channels, out_channels=out_channels, kernel_size=1, stride=1),
            nn.BatchNorm2d(out_channels),
        )

        if self.use_pool:
            self.shortcut = nn.Sequential(
                nn.MaxPool2d(kernel_size=stride, stride=stride),
                nn.Conv2d(in_channels=in_channels, out_channels=out_channels, kernel_size=1, stride=1),
                nn.BatchNorm2d(out_channels),
            )

        self.relu = nn.SiLU(inplace=True)

    def forward(self, x):
        branch1 = self.branch1(x)
        out = (branch1 + self.shortcut(x)) if self.use_pool else (branch1 + x)
        return self.relu(out)
    
    
class SPP(nn.Module):
    # Spatial pyramid pooling layer used in YOLOv3-SPP
    def __init__(self, c1, c2, k=(5, 9, 13)):
        super(SPP, self).__init__()
        c_ = c1 // 2  # hidden channels
        self.cv1 = Conv(c1, c_, 1, 1)
        self.cv2 = Conv(c_ * (len(k) + 1), c2, 1, 1)
        self.m = nn.ModuleList([nn.MaxPool2d(kernel_size=x, stride=1, padding=x // 2) for x in k])

    def forward(self, x):
        x = self.cv1(x)
        return self.cv2(torch.cat([x] + [m(x) for m in self.m], 1))


class Focus(nn.Module):
    # Focus wh information into c-space
    def __init__(self, c1, c2, k=1, s=1, p=None, g=1, act=True):  # ch_in, ch_out, kernel, stride, padding, groups
        super(Focus, self).__init__()
        self.conv = Conv(c1 * 4, c2, k, s, p, g, act)
        # self.contract = Contract(gain=2)

    def forward(self, x):  # x(b,c,w,h) -> y(b,4c,w/2,h/2)
        return self.conv(torch.cat([x[..., ::2, ::2], x[..., 1::2, ::2], x[..., ::2, 1::2], x[..., 1::2, 1::2]], 1))
        # return self.conv(self.contract(x))


class Contract(nn.Module):
    # Contract width-height into channels, i.e. x(1,64,80,80) to x(1,256,40,40)
    def __init__(self, gain=2):
        super().__init__()
        self.gain = gain

    def forward(self, x):
        N, C, H, W = x.size()  # assert (H / s == 0) and (W / s == 0), 'Indivisible gain'
        s = self.gain
        x = x.view(N, C, H // s, s, W // s, s)  # x(1,64,40,2,40,2)
        x = x.permute(0, 3, 5, 1, 2, 4).contiguous()  # x(1,2,2,64,40,40)
        return x.view(N, C * s * s, H // s, W // s)  # x(1,256,40,40)


class Expand(nn.Module):
    # Expand channels into width-height, i.e. x(1,64,80,80) to x(1,16,160,160)
    def __init__(self, gain=2):
        super().__init__()
        self.gain = gain

    def forward(self, x):
        N, C, H, W = x.size()  # assert C / s ** 2 == 0, 'Indivisible gain'
        s = self.gain
        x = x.view(N, s, s, C // s ** 2, H, W)  # x(1,2,2,16,80,80)
        x = x.permute(0, 3, 4, 1, 5, 2).contiguous()  # x(1,16,80,2,80,2)
        return x.view(N, C // s ** 2, H * s, W * s)  # x(1,16,160,160)


class Concat(nn.Module):
    # Concatenate a list of tensors along dimension
    def __init__(self, dimension=1):
        super(Concat, self).__init__()
        self.d = dimension

    def forward(self, x):
        return torch.cat(x, self.d)


class NMS(nn.Module):
    # Non-Maximum Suppression (NMS) module
    conf = 0.25  # confidence threshold
    iou = 0.45  # IoU threshold
    classes = None  # (optional list) filter by class

    def __init__(self):
        super(NMS, self).__init__()

    def forward(self, x):
        return non_max_suppression(x[0], conf_thres=self.conf, iou_thres=self.iou, classes=self.classes)

class autoShape(nn.Module):
    # input-robust model wrapper for passing cv2/np/PIL/torch inputs. Includes preprocessing, inference and NMS
    img_size = 640  # inference size (pixels)
    conf = 0.25  # NMS confidence threshold
    iou = 0.45  # NMS IoU threshold
    classes = None  # (optional list) filter by class

    def __init__(self, model):
        super(autoShape, self).__init__()
        self.model = model.eval()

    def autoshape(self):
        print('autoShape already enabled, skipping... ')  # model already converted to model.autoshape()
        return self

    def forward(self, imgs, size=640, augment=False, profile=False):
        # Inference from various sources. For height=720, width=1280, RGB images example inputs are:
        #   filename:   imgs = 'data/samples/zidane.jpg'
        #   URI:             = 'https://github.com/ultralytics/yolov5/releases/download/v1.0/zidane.jpg'
        #   OpenCV:          = cv2.imread('image.jpg')[:,:,::-1]  # HWC BGR to RGB x(720,1280,3)
        #   PIL:             = Image.open('image.jpg')  # HWC x(720,1280,3)
        #   numpy:           = np.zeros((720,1280,3))  # HWC
        #   torch:           = torch.zeros(16,3,720,1280)  # BCHW
        #   multiple:        = [Image.open('image1.jpg'), Image.open('image2.jpg'), ...]  # list of images

        p = next(self.model.parameters())  # for device and type
        if isinstance(imgs, torch.Tensor):  # torch
            return self.model(imgs.to(p.device).type_as(p), augment, profile)  # inference

        # Pre-process
        n, imgs = (len(imgs), imgs) if isinstance(imgs, list) else (1, [imgs])  # number of images, list of images
        shape0, shape1 = [], []  # image and inference shapes
        for i, im in enumerate(imgs):
            if isinstance(im, str):  # filename or uri
                im = Image.open(requests.get(im, stream=True).raw if im.startswith('http') else im)  # open
            im = np.array(im)  # to numpy
            if im.shape[0] < 5:  # image in CHW
                im = im.transpose((1, 2, 0))  # reverse dataloader .transpose(2, 0, 1)
            im = im[:, :, :3] if im.ndim == 3 else np.tile(im[:, :, None], 3)  # enforce 3ch input
            s = im.shape[:2]  # HWC
            shape0.append(s)  # image shape
            g = (size / max(s))  # gain
            shape1.append([y * g for y in s])
            imgs[i] = im  # update
        shape1 = [make_divisible(x, int(self.stride.max())) for x in np.stack(shape1, 0).max(0)]  # inference shape
        x = [letterbox(im, new_shape=shape1, auto=False)[0] for im in imgs]  # pad
        x = np.stack(x, 0) if n > 1 else x[0][None]  # stack
        x = np.ascontiguousarray(x.transpose((0, 3, 1, 2)))  # BHWC to BCHW
        x = torch.from_numpy(x).to(p.device).type_as(p) / 255.  # uint8 to fp16/32

        # Inference
        with torch.no_grad():
            y = self.model(x, augment, profile)[0]  # forward
        y = non_max_suppression(y, conf_thres=self.conf, iou_thres=self.iou, classes=self.classes)  # NMS

        # Post-process
        for i in range(n):
            scale_coords(shape1, y[i][:, :4], shape0[i])

        return Detections(imgs, y, self.names)


class Detections:
    # detections class for YOLOv5 inference results
    def __init__(self, imgs, pred, names=None):
        super(Detections, self).__init__()
        d = pred[0].device  # device
        gn = [torch.tensor([*[im.shape[i] for i in [1, 0, 1, 0]], 1., 1.], device=d) for im in imgs]  # normalizations
        self.imgs = imgs  # list of images as numpy arrays
        self.pred = pred  # list of tensors pred[0] = (xyxy, conf, cls)
        self.names = names  # class names
        self.xyxy = pred  # xyxy pixels
        self.xywh = [xyxy2xywh(x) for x in pred]  # xywh pixels
        self.xyxyn = [x / g for x, g in zip(self.xyxy, gn)]  # xyxy normalized
        self.xywhn = [x / g for x, g in zip(self.xywh, gn)]  # xywh normalized
        self.n = len(self.pred)

    def display(self, pprint=False, show=False, save=False, render=False):
        colors = color_list()
        for i, (img, pred) in enumerate(zip(self.imgs, self.pred)):
            str = f'Image {i + 1}/{len(self.pred)}: {img.shape[0]}x{img.shape[1]} '
            if pred is not None:
                for c in pred[:, -1].unique():
                    n = (pred[:, -1] == c).sum()  # detections per class
                    str += f'{n} {self.names[int(c)]}s, '  # add to string
                if show or save or render:
                    img = Image.fromarray(img.astype(np.uint8)) if isinstance(img, np.ndarray) else img  # from np
                    for *box, conf, cls in pred:  # xyxy, confidence, class
                        # str += '%s %.2f, ' % (names[int(cls)], conf)  # label
                        ImageDraw.Draw(img).rectangle(box, width=4, outline=colors[int(cls) % 10])  # plot
            if pprint:
                print(str)
            if show:
                img.show(f'Image {i}')  # show
            if save:
                f = f'results{i}.jpg'
                str += f"saved to '{f}'"
                img.save(f)  # save
            if render:
                self.imgs[i] = np.asarray(img)

    def print(self):
        self.display(pprint=True)  # print results

    def show(self):
        self.display(show=True)  # show results

    def save(self):
        self.display(save=True)  # save results

    def render(self):
        self.display(render=True)  # render results
        return self.imgs

    def __len__(self):
        return self.n

    def tolist(self):
        # return a list of Detections objects, i.e. 'for result in results.tolist():'
        x = [Detections([self.imgs[i]], [self.pred[i]], self.names) for i in range(self.n)]
        for d in x:
            for k in ['imgs', 'pred', 'xyxy', 'xyxyn', 'xywh', 'xywhn']:
                setattr(d, k, getattr(d, k)[0])  # pop out of list
        return x


class Classify(nn.Module):
    # Classification head, i.e. x(b,c1,20,20) to x(b,c2)
    def __init__(self, c1, c2, k=1, s=1, p=None, g=1):  # ch_in, ch_out, kernel, stride, padding, groups
        super(Classify, self).__init__()
        self.aap = nn.AdaptiveAvgPool2d(1)  # to x(b,c1,1,1)
        self.conv = nn.Conv2d(c1, c2, k, s, autopad(k, p), groups=g)  # to x(b,c2,1,1)
        self.flat = nn.Flatten()

    def forward(self, x):
        z = torch.cat([self.aap(y) for y in (x if isinstance(x, list) else [x])], 1)  # cat if list
        return self.flat(self.conv(z))  # flatten to x(b,c2)
